Objective: There is ongoing concern about the impact of electroconvulsive therapy (ECT) on cognition in patients with late-life depression (LLD), especially in patients for whom pretreatment Mini-Mental State Exam (MMSE) scores are low. Our aim was to examine the evolution of cognitive effects of ECT, using the MMSE in a large group of patients with LLD. Methods: One hundred nine patients aged 55 years and older with unipolar depression, referred for ECT, were included in our study. The MMSE was assessed before, during, immediately after, and 6 months after ECT. Results: MMSE scores improved significantly during the course of ECT and remained stable during the 6-month period after ending ECT for the total group. In the group of patients with a low MMSE score (<24) at baseline, the MMSE score improved significantly during ECT, whereas in the group of patients with a normal MMSE score (≥24) at baseline, the score did not change significantly during ECT. In both groups, MMSE scores still increased slightly after ECT was discontinued. Conclusion: ECT does not cause deleterious cognitive effects, as measured with the MMSE, during and for 6 months after the ECT course in patients with LLD. In the event of a baseline cognitive impairment, MMSE scores tend to improve significantly during and for 6 months after the ECT course. The presence of pretreatment cognitive impairment should not lead clinicians to withhold ECT in older patients with severe depression.